feat: add sync progress tracking with image download status

- Service worker reports image caching progress back to main thread
- Sync progress shows current phase (recipes, pages, data, images)
- Display progress bar for image downloads in sync tooltip
- Use mediapath for thumbnail URLs (with hash for cache busting)
- Serve cached thumbnails as fallback for full/placeholder when offline

src/lib/components/OfflineSyncButton.svelte

@@ -146,6 +146,31 @@
 		font-size: 0.75rem;
 		color: var(--nord4);
 	}
+
+	.progress-container {
+		display: flex;
+		flex-direction: column;
+		gap: 0.25rem;
+	}
+
+	.progress-text {
+		font-size: 0.75rem;
+		color: var(--nord4);
+	}
+
+	.progress-bar {
+		width: 100%;
+		height: 4px;
+		background: var(--nord3);
+		border-radius: 2px;
+		overflow: hidden;
+	}
+
+	.progress-fill {
+		height: 100%;
+		background: var(--nord14);
+		transition: width 150ms ease-out;
+	}
 </style>
 
 {#if mounted && pwaStore.isStandalone}
@@ -204,6 +229,20 @@
 						</button>
 					{/if}
 
+					{#if pwaStore.isSyncing && pwaStore.syncProgress}
+						<div class="progress-container">
+							<div class="progress-text">{pwaStore.syncProgress.message}</div>
+							{#if pwaStore.syncProgress.imageProgress}
+								<div class="progress-bar">
+									<div
+										class="progress-fill"
+										style="width: {(pwaStore.syncProgress.imageProgress.completed / pwaStore.syncProgress.imageProgress.total) * 100}%"
+									></div>
+								</div>
+							{/if}
+						</div>
+					{/if}
+
 					{#if pwaStore.error}
 						<div class="status" style="color: var(--nord11);">
 							{pwaStore.error}

src/lib/offline/sync.ts

@@ -12,16 +12,31 @@ const glaubeRoutes = Object.keys(glaubePageModules).map(path => {
 		.replace('/+page.svelte', '') || '/glaube';
 });
 
+export type SyncProgress = {
+	phase: 'recipes' | 'pages' | 'data' | 'images';
+	message: string;
+	imageProgress?: {
+		completed: number;
+		total: number;
+	};
+};
+
 export type SyncResult = {
 	success: boolean;
 	recipeCount: number;
 	error?: string;
 };
 
+export type SyncProgressCallback = (progress: SyncProgress) => void;
+
 export async function downloadAllRecipes(
-	fetchFn: typeof fetch = fetch
+	fetchFn: typeof fetch = fetch,
+	onProgress?: SyncProgressCallback
 ): Promise<SyncResult> {
 	try {
+		// Phase 1: Download recipe data
+		onProgress?.({ phase: 'recipes', message: 'Downloading recipes...' });
+
 		const response = await fetchFn('/api/rezepte/offline-db');
 
 		if (!response.ok) {
@@ -36,15 +51,29 @@ export async function downloadAllRecipes(
 
 		// Save to IndexedDB
 		await saveAllRecipes(data.brief, data.full);
+		onProgress?.({ phase: 'recipes', message: `Saved ${data.brief.length} recipes` });
 
-		// Pre-cache the main recipe pages HTML (needed for offline shell)
+		// Phase 2: Pre-cache the main pages HTML
+		onProgress?.({ phase: 'pages', message: 'Caching pages...' });
 		await precacheMainPages(fetchFn);
 
-		// Pre-cache __data.json for all recipes (needed for client-side navigation)
+		// Phase 3: Pre-cache __data.json for all recipes
+		onProgress?.({ phase: 'data', message: 'Caching navigation data...' });
 		await precacheRecipeData(data.brief);
 
-		// Pre-cache thumbnail images via service worker
-		await precacheThumbnails(data.brief);
+		// Phase 4: Pre-cache thumbnail images via service worker
+		onProgress?.({ phase: 'images', message: 'Caching images...', imageProgress: { completed: 0, total: data.brief.length } });
+
+		await precacheThumbnails(data.brief, (imgProgress) => {
+			onProgress?.({
+				phase: 'images',
+				message: `Caching images (${imgProgress.completed}/${imgProgress.total})...`,
+				imageProgress: {
+					completed: imgProgress.completed,
+					total: imgProgress.total
+				}
+			});
+		});
 
 		return {
 			success: true,
@@ -184,28 +213,71 @@ async function precacheRecipeData(recipes: BriefRecipeType[]): Promise<void> {
 	}
 }
 
-async function precacheThumbnails(recipes: BriefRecipeType[]): Promise<void> {
+type ImageCacheProgress = {
+	completed: number;
+	total: number;
+	done: boolean;
+};
+
+type ProgressCallback = (progress: ImageCacheProgress) => void;
+
+async function precacheThumbnails(
+	recipes: BriefRecipeType[],
+	onProgress?: ProgressCallback
+): Promise<void> {
 	// Only attempt if service worker is available
 	if (!('serviceWorker' in navigator)) return;
 
 	const registration = await navigator.serviceWorker.ready;
 	if (!registration.active) return;
 
-	// Collect all thumbnail URLs
+	// Collect all thumbnail URLs using mediapath (includes hash for cache busting)
 	const thumbnailUrls: string[] = [];
 	for (const recipe of recipes) {
 		if (recipe.images && recipe.images.length > 0) {
 			const mediapath = recipe.images[0].mediapath;
-			// Thumbnail path format: /static/rezepte/thumb/{short_name}.webp
-			thumbnailUrls.push(`/static/rezepte/thumb/${recipe.short_name}.webp`);
+			// Thumbnail path format: /static/rezepte/thumb/{mediapath}
+			thumbnailUrls.push(`/static/rezepte/thumb/${mediapath}`);
 		}
 	}
 
-	// Send message to service worker to cache these URLs
-	if (thumbnailUrls.length > 0) {
-		registration.active.postMessage({
+	if (thumbnailUrls.length === 0) return;
+
+	// Generate unique request ID
+	const requestId = `img-${Date.now()}-${Math.random().toString(36).slice(2)}`;
+
+	// Create a promise that resolves when caching is complete
+	return new Promise((resolve) => {
+		function handleMessage(event: MessageEvent) {
+			if (event.data?.type === 'CACHE_IMAGES_PROGRESS' && event.data.requestId === requestId) {
+				if (onProgress) {
+					onProgress({
+						completed: event.data.completed,
+						total: event.data.total,
+						done: event.data.done
+					});
+				}
+
+				if (event.data.done) {
+					navigator.serviceWorker.removeEventListener('message', handleMessage);
+					resolve();
+				}
+			}
+		}
+
+		navigator.serviceWorker.addEventListener('message', handleMessage);
+
+		// Send message to service worker to cache these URLs
+		registration.active!.postMessage({
 			type: 'CACHE_IMAGES',
-			urls: thumbnailUrls
+			urls: thumbnailUrls,
+			requestId
 		});
-	}
+
+		// Timeout fallback in case messages don't arrive
+		setTimeout(() => {
+			navigator.serviceWorker.removeEventListener('message', handleMessage);
+			resolve();
+		}, 5 * 60 * 1000); // 5 minute timeout
+	});
 }

src/lib/stores/pwa.svelte.ts

@@ -1,6 +1,6 @@
 import { browser } from '$app/environment';
 import { isOfflineDataAvailable, getLastSync, clearOfflineData } from '$lib/offline/db';
-import { downloadAllRecipes, type SyncResult } from '$lib/offline/sync';
+import { downloadAllRecipes, type SyncResult, type SyncProgress } from '$lib/offline/sync';
 
 const AUTO_SYNC_INTERVAL = 30 * 60 * 1000; // 30 minutes
 const LAST_SYNC_KEY = 'bocken-last-sync-time';
@@ -13,6 +13,7 @@ type PWAState = {
 	error: string | null;
 	isStandalone: boolean;
 	isInitialized: boolean;
+	syncProgress: SyncProgress | null;
 };
 
 function createPWAStore() {
@@ -23,7 +24,8 @@ function createPWAStore() {
 		recipeCount: 0,
 		error: null,
 		isStandalone: false,
-		isInitialized: false
+		isInitialized: false,
+		syncProgress: null
 	});
 
 	let autoSyncInterval: ReturnType<typeof setInterval> | null = null;
@@ -96,6 +98,9 @@ function createPWAStore() {
 		get isInitialized() {
 			return state.isInitialized;
 		},
+		get syncProgress() {
+			return state.syncProgress;
+		},
 
 		async initialize() {
 			if (!browser || state.isInitialized) return;
@@ -185,9 +190,12 @@ function createPWAStore() {
 
 			state.isSyncing = true;
 			state.error = null;
+			state.syncProgress = null;
 
 			try {
-				const result = await downloadAllRecipes(fetchFn);
+				const result = await downloadAllRecipes(fetchFn, (progress) => {
+					state.syncProgress = progress;
+				});
 
 				if (result.success) {
 					state.isOfflineAvailable = true;
@@ -201,6 +209,7 @@ function createPWAStore() {
 				return result;
 			} finally {
 				state.isSyncing = false;
+				state.syncProgress = null;
 			}
 		},
 

src/service-worker.ts

@@ -113,27 +113,47 @@ sw.addEventListener('fetch', (event) => {
 		return;
 	}
 
-	// Handle recipe images (thumbnails and full images)
+	// Handle recipe images (thumbnails, full images, and placeholders)
 	if (
 		url.pathname.startsWith('/static/rezepte/') &&
-		(url.pathname.includes('/thumb/') || url.pathname.includes('/full/'))
+		(url.pathname.includes('/thumb/') || url.pathname.includes('/full/') || url.pathname.includes('/placeholder/'))
 	) {
 		event.respondWith(
-			caches.open(CACHE_IMAGES).then((cache) =>
-				cache.match(event.request).then((cached) => {
-					if (cached) return cached;
+			(async () => {
+				const cache = await caches.open(CACHE_IMAGES);
 
-					return fetch(event.request).then((response) => {
-						if (response.ok) {
+				// Try exact match first
+				const cached = await cache.match(event.request);
+				if (cached) return cached;
+
+				// Try to fetch from network
+				try {
+					const response = await fetch(event.request);
+					if (response.ok) {
+						// Cache thumbnails for offline use
+						if (url.pathname.includes('/thumb/')) {
 							cache.put(event.request, response.clone());
 						}
-						return response;
-					}).catch(() => {
-						// Return a placeholder or let the browser handle the error
-						return new Response('', { status: 404 });
-					});
-				})
-			)
+					}
+					return response;
+				} catch {
+					// Network failed - try to serve thumbnail as fallback for full/placeholder
+					if (url.pathname.includes('/full/') || url.pathname.includes('/placeholder/')) {
+						// Extract filename and try to find cached thumbnail
+						const filename = url.pathname.split('/').pop();
+						if (filename) {
+							const thumbUrl = `/static/rezepte/thumb/${filename}`;
+							const thumbCached = await cache.match(thumbUrl);
+							if (thumbCached) {
+								return thumbCached;
+							}
+						}
+					}
+
+					// No fallback available
+					return new Response('', { status: 404 });
+				}
+			})()
 		);
 		return;
 	}
@@ -243,16 +263,35 @@ sw.addEventListener('message', (event) => {
 
 	if (event.data?.type === 'CACHE_IMAGES') {
 		const urls: string[] = event.data.urls;
-		caches.open(CACHE_IMAGES).then((cache) => {
+		const requestId = event.data.requestId;
+
+		caches.open(CACHE_IMAGES).then(async (cache) => {
 			// Cache images in batches to avoid overwhelming the network
 			const batchSize = 10;
-			let index = 0;
+			const total = urls.length;
+			let completed = 0;
 
-			function cacheBatch() {
-				const batch = urls.slice(index, index + batchSize);
-				if (batch.length === 0) return;
+			// Report progress to all clients
+			async function reportProgress(done: boolean = false) {
+				const clients = await sw.clients.matchAll();
+				for (const client of clients) {
+					client.postMessage({
+						type: 'CACHE_IMAGES_PROGRESS',
+						requestId,
+						completed,
+						total,
+						done
+					});
+				}
+			}
 
-				Promise.all(
+			// Report initial state
+			await reportProgress();
+
+			for (let i = 0; i < urls.length; i += batchSize) {
+				const batch = urls.slice(i, i + batchSize);
+
+				await Promise.all(
 					batch.map((url) =>
 						fetch(url)
 							.then((response) => {
@@ -263,17 +302,23 @@ sw.addEventListener('message', (event) => {
 							.catch(() => {
 								// Ignore failed image fetches
 							})
+							.finally(() => {
+								completed++;
+							})
 					)
-				).then(() => {
-					index += batchSize;
-					if (index < urls.length) {
-						// Small delay between batches
-						setTimeout(cacheBatch, 100);
-					}
-				});
+				);
+
+				// Report progress after each batch
+				await reportProgress();
+
+				// Small delay between batches
+				if (i + batchSize < urls.length) {
+					await new Promise((resolve) => setTimeout(resolve, 100));
+				}
 			}
 
-			cacheBatch();
+			// Report completion
+			await reportProgress(true);
 		});
 	}